1. Field of Invention
The present invention relates to ceramic composites and, in particular, to transparent ceramic armor.
2. Discussion of Related Art
Ceramics exhibit a variety of properties that make them useful in products subjected to, for example, abrasion, high temperatures or high speed impacts. An excellent strength to weight ratio and superior hardness mean that ceramics can often replace and improve on structural materials such as steel, polymers and glass. Ceramic composites are materials that include a ceramic bonded to another ceramic or to a non-ceramic material. For example, a ceramic sheet can be bonded to glass or plastic or another ceramic to form a ceramic composite. Ceramic composites may allow the useful properties of ceramics to be exploited while providing a product that is, for example, lighter, more flexible or less expensive than a purely ceramic material.
Ceramics can be opaque, translucent or transparent. Transparent ceramics are of particular interest because they can provide an impact resistant, scratch resistant and heat resistant material that can replace transparent glass or polymers. While ceramic sheets are typically more expensive to produce than are glass or polymeric sheets, the superior properties of ceramics may make them the material of choice for use in small windows where scratch resistance, high strength and transmission of light are desired under extreme conditions or in harsh environments.
Composites of ceramic and other materials such as glass and polycarbonate have been suggested as impact resistant transparent armor. For example, United States Statutory Invention Registration No. H1567 describes a transparent composite armor having a hard frangible face plate backed by a more resilient plate. United States Statutory Invention Registration No. H1519 describes the bonding of transparent aluminum oxide or magnesium oxide to a backup plate of transparent plastic. However, to provide sufficient transparency and strength, these composites may be thick, heavy, and expensive and may only be available in small sizes that provide for limited viewing areas. As a result, ceramic composites have not been widely used as transparent armor. Advancements in the field that can, for example, reduce weight and cost while increasing surface area should lead to improved armor and to greater use of ceramics in this field.